Somewhere Over the Rainbow

Avi Loeb
5 min readJun 24, 2023


Diary of an Interstellar Voyage, Report 25

(June 24, 2023)

A rainbow appeared above Silver Star’s deck after the expedition team retrieved the harvest of Run 13, which included the biggest spherule so far with an enhanced abundance of rare elements — often used in semiconductors.

Perhaps I was not clear enough in my preceding 24 diary reports on the expedition to retrieve the remains of the first recognized interstellar meteor, IM1. So let me state the obvious at the top of this 25th report.

The Interstellar Expedition story is about new evidence regarding interstellar objects and not about opinions. That people tend to express an opinion about the unknown before evidence is gathered, poses an unfortunate impediment on the growth of our scientific knowledge. I was told that a scientist not involved in our expedition will discuss the expedition at a conference next week. This misses the point that new scientific knowledge is advanced by those who know the evidence and not by those who ruminate on past knowledge.

So what is the evidence we collected so far from the Interstellar Expedition? Run 8 dominated the spherule count by an order of magnitude relative to all other runs and its line skimmed the upper envelope of the likely interstellar meteor (IM1) path. Most other lines, including those in control areas, did not find spherules larger than 300 microns. The early part of Run 8 overlapped with Run 5, which showed spherules of smaller characteristic size. This is consistent with the smaller spherules falling closer to the fireball site as a result of their enhanced friction with air. The composition of the spherules deviates from those of known meteors from the solar system including iron meteorites. Some of the overabundant elements in IM1’s spherules are commonly used in electric circuitry and semiconductors.

Sunrise at 5:30AM after a 4AM Zoom session with the Galileo Project team in the US, followed by a jog on the open deck of Silver Star (June 24, 2023). Earlier, Loeb accidentally wounded his shin as he was climbing up the stairs.

My carry-on luggage on route to the expedition included 20 bars of dark chocolate that I eat every day after my 30-minute jog at sunrise. By the time the expedition is over, I will replace the emptied luggage space with spherules from the expedition. It is important to avoid eating the returned content by mistake, because that would require spherule retrieval in the operating room of Mass General after my return to Boston.

On my way home, I will make a stop at Ryan Weed’s lab on the campus of UC Berkeley where we will attempt a complete census of the composition of our spherules with state-of-the-art diagnostics. As we were making plans, I told Ryan: “We are on the same boat, both literally and figuratively.”

Run 14 delivered a small seashell coated with magnetite and a pile of black powder which we vacuumed and delivered to the analysis team.

As we approached the sled of Run 14, we noticed a small seashell attached to a magnet in the back.

The spherule count is currently at 19. Champagne will be served at dinner.

Vacuuming and scooping all the magnetic material from the sled’s magnets in Run 14.

Our next expedition will aim to retrieve any large remnant left over from IM1. At our expedition leadership meeting last evening, we decided to use an analog 30 kHz sonar owned by the senior team members Art Wright and Mike Williamson. This sonar system achieves a resolution of a few centimeters. IM1's fireball exhibited three flares, potentially related to multiple pieces that broke off the initial object. We should search for these pieces on the ocean floor. Our team member Michael Kelly noted: “I love the ocean. When you go out to sea, you never know what you are about to see.”

The record holder spherule from Run 14 i the merger product of multiple molten iron droplets before they solidified. Its length is 0.7 millimeter and its composition is similar to other spherules.

Art and Mike were about to discard the 30 kHz sonar after decades of use. Now it will be given a new life. I love the idea of rejuvenating an old system to pursue new research at the frontiers of science. Living for two decades in a house that is over a century old, taught me to appreciate old-fashioned craftsmanship. That Art Wright in his eighties masters the art of always being right is another illustration of the same theme. Art has always been successful in his expeditions including this one.

After the expedition team retrieved Run 13, a rainbow appeared above Silver Star’s deck. Hours later, we realized that this run delivered the biggest spherule so far with an enhanced abundance of rare elements — often used in semiconductors. Poetically, I was reminded of the words of Judy Garland’s song:

“Somewhere over the rainbow
Skies are blue
And the dreams that you dare to dream
Really do come true.”


Avi Loeb is the head of the Galileo Project, founding director of Harvard University’s — Black Hole Initiative, director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, and the former chair of the astronomy department at Harvard University (2011–2020). He chairs the advisory board for the Breakthrough Starshot project, and is a former member of the President’s Council of Advisors on Science and Technology and a former chair of the Board on Physics and Astronomy of the National Academies. He is the bestselling author of “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” and a co-author of the textbook “Life in the Cosmos”, both published in 2021. His new book, titled “Interstellar”, is scheduled for publication in August 2023.



Avi Loeb

Avi Loeb is the Baird Professor of Science and Institute director at Harvard University and the bestselling author of “Extraterrestrial” and "Interstellar".